html {
    font-size: 10px;
}

body {
    font-family: -apple-system, BlinkMacSystemFont,"Helvetia Neue","PingFang SC","Microsoft SC","Microsoft YaHei","Source Han Sans SC",
    "Noto Sans CJK","WenQuanYi Micro Hei",sans-serif;
    font-size: 16px;
    background-image: url(http://a1.jikexueyuan.com/home/201508/25/ccd7/55dbca0c40d6f.jpg);
    background: rgb(2,0,36);
    background: linear-gradient(0.25turn, #3f87a6, #ebf8e1, #f69d3c);
    background-repeat: no-repeat;
    background-position: 50% 50%;
}

h1 {
    font-weight: bolder;
    /* font-size: 1mm; */
    text-align: center;
    letter-spacing: -2px;
    /* text-decoration: underline; */
   }

footer {
    border-top: 1px solid #ccc;
    margin-top: 5rem;
}

footer p {
    text-align: center;
    margin-top: 5rem;
}

footer {
    text-align: center;
    text-indent: 0;
    font-size: 12px;
}

footer span {
    margin: 0 2rem;
}

